1. Field of the Invention
The present invention generally relates to a system and method for removing asbestos-containing materials from buildings and, more particularly, the present invention relates to a system and method for removing asbestos-containing materials such as fireproofing and sprayed-on acoustical insulation.
2. State of the Art
Asbestos is a natural mineral whose extraordinary physical resistance to heat and chemicals has been recognized for centuries. In fact, the name asbestos comes from a Greek derivative which signifies that the mineral is durable and will not burn. Because of its fireproofing and thermal insulating properties, as well as its natural abundance in underground deposits, asbestos was a major component of building materials for a number of years, particularly between 1950 and 1974. During that period, thousands of tons of asbestos were sprayed into buildings to provide fireproofing and acoustical insulation. Also, asbestos was widely applied as thermal insulation for water pipes as well as heating and ventilating ducts. Typically in such instances, the asbestos-containing material is a composite dry mixture including asbestos fibers and particles. The mixture is held together by a glue-like binder which also bonds the material to a substrate such as metal and wooden decking, metal beams, plaster surfaces, and concrete pillars and beams.
By the early 1970's, accumulated medical information indicated that exposure to airborne asbestos could pose serious hazards to health. In particular, links were found between exposure to friable asbestos and diseases such as asbestosis, mesothelioma, and cancer of the lung. (Friable asbestos is material that is easily crumbled by hand pressure; it should be noted that asbestos-containing materials that are non-friable while in situ can become friable upon removal.) Because of the medical concerns, spraying of asbestos was banned in 1973 by the U.S. Environmental Protection Agency (EPA). Subsequently, most applications of asbestos in construction materials have been eliminated or are being phased out.
Due to the medical hazards of asbestos in existing structures, a range of corrective and mitigating measures have come into practice. The purpose of such measures is to protect the public, building occupants, maintenance persons, and personnel who could disturb asbestos materials during construction work. To alleviate risks of human exposure to airborne asbestos particles, current practice is to remove most forms of asbestos-containing materials whenever buildings are remodeled or renovated.
Procedures to remove asbestos from buildings usually encompass several key steps. Those steps include: (1) protecting workers in asbestos-containing areas by means of respirators, protective clothing and decontamination systems; (2) fully isolating asbestos-containing areas by means of sheet plastic that is sealed in place; (3) controlling ingress and egress to asbestos-containing work area by means of decontamination system; (4) minimizing airborne asbestos fiber concentrations in asbestos removal work areas by fully wetting asbestos-containing materials with water and penetration-aiding surfactants; (5) controlling and collecting wetted asbestos-containing materials while they are still wet, and depositing the collected materials in sealable bags; and (6) disposing of collected asbestos-containing waste materials at approved sites in a manner which avoids public exposure when the waste is transported and buried. Many of these procedures are set forth in EPA regulations (40 CFR, Part 61, Subparts A & B, 1973).
Normally, the initial step in removing asbestos-containing materials such as fireproofing and sprayed-on acoustical insulation is to repeatedly wet the materials to obtain maximum saturation. Two advantages of the use of water during asbestos removal include a reduction in airborne asbestos fiber concentrations and a reduction in the effort required to remove the asbestos-containing materials. That is, wet removal techniques are based on the tendency of water to reduce the release of the airborne asbestos fibers from asbestos-containing material and to increase the settling rate of fibers that are released. The positive effects of wet removal are sometimes further enhanced by adding a wetting agent to the water. Conventional wetting agents are combinations of chemicals that aid in the penetration of the asbestos-containing materials and increase the probability of individual fiber wetting. Various wetting agents are well known, and the EPA recommends a wetting agent consisting of 50% polyoxyethylene ester and 50% polyoxyethylene ether in a ratio of 1 ounce to 5 gallons of water.
After wetting, the typical next step in removing asbestos-containing materials from a substrate is to manually scrape the substrate by means of metal scrapers such as paint scrapers and tile removal scrapers. After gross removal of asbestos by scraping, residual asbestos-containing material is further cleaned or "detailed" from the substrate by scrubbing with brushes, scrub pads, sponges and rags. After cleaning of the substrate, the removed asbestos-containing materials are manually collected by means of shovels, squeegees, mops, or the like. Also, vacuums have been used to collect waste asbestos-containing materials from work sites.
At this juncture, it can be appreciated that asbestos removal from buildings is of substantial concern and is expensive, time consuming and potentially hazardous. The extent of the removal task may be appreciated from the fact that carcinogenic asbestos fibers have been used in the construction of more than 700,000 buildings throughout the U.S. Such asbestos was most often sprayed between floors, on steel girders, in wall panels and in other locations in which removal work is difficult or inconvenient.
Although asbestos removal is commonly performed by a manual scraping of a substrate as described above, it is known that faster removal can be achieved by forcefully directing high pressure water against an asbestos-containing material. Such procedures are sometimes referred to as hydroblasting and involve emitting water at high velocities and in relatively large quantities, e.g., 4-6 gal/min., to mechanically dislodge the asbestos from the substrate. One drawback of hydroblasting is that, in multi-floor work environments, considerable effort is required to collect and contain the water before it leaks to lower floors or causes water damage and electrical short-outs. Also, water leakage during hydroblasting operations can disperse contaminating particles. Further, after hydroblasting water is collected and contained, it must either be filtered or disposed of as hazardous waste. Therefore, hydroblasting is generally ill-suited to gross removal of asbestos but often is better limited to detailing work requiring usage of relatively limited quantities of water.
In view of the preceding discussion, it can be appreciated that there is a need to provide improved methods and systems for removing asbestos-containing materials from substrates.